Grayslake police said shortly before 10:15 a.m. there was a fatal crash near the intersection of Washington Street and Atkinson Road.
Police said their initial investigation found a Ford Escape and a Ford F-350 with an attached trailer crashed, pushing the F-350 off the roadway. That truck struck a pedestrian standing near the intersection.
The pedestrian, identified only as an 18-year-old resident of Grayslake, was taken to the hospital in critical condition and later died.
Both drivers suffered non-life threatening injuries, police said.
The crash remains under investigation by the Grayslake Police Department and Lake County Major Crash Assistance Team. No further information has been released.